Infections caused by or related to bacteria are a major cause of human illness worldwide, and the frequency of resistance to standard antibiotics has risen dramatically over the last decade. Hence, there exists an unmet medical need and demand for new anti-microbial agents against pathogenic bacteria, as well as drug screening methods to identify such agents.
An example of a bacterial enzyme that is resistant to a widely used antibacterial agent, Triclosan, is FabK. This enzyme, involved in fatty acid biosynthesis, has been recently reported from Streptococcus pneumoniae, a well-known human pathogen (Heath, et al. Nature 406: 145 (2000)). The specific activity of the enzyme under the published conditions was 64+/−4 nmol min−1, too low to efficiently screen for compounds that modulate the activity of the enzyme, such as inhibitors (Heath, et al. Nature 406: 145 (2000)). The present invention solves this problem by providing a method for screening for FabK agonists and antagonists, wherein FabK activity is sufficient to perform efficient compound screening.
A further problem identified by recent studies has been solved by this invention. Heath teaches that organisms expressing FabK will be refractory to FabI inhibitors, and that bacteria possessing both targets will require a combination of inhibitors to block growth (Heath, et al. Nature 406: 145 (2000)). The present invention provides methods of screening for compounds that inhibit both enzymes, as well as the use of such compounds as antimicrobial compounds.